A journey to Pangaea

[Mendalla]

I have written before about PBS Eons, one of the PBS Digital Studios family of YouTube channels, which is produced for PBS by Complexly, the creator-owned non-profit production company started by author and influencer Hank Green. This week, they embarked on an interesting and exciting new venture with PBS: a six part series to be run on PBS's website and app on the history of the Permian Period. The title is Eons: Life and Death on Pangaea.

The Permian is a critical period in the evolution of life, marking the evolution of the two groups of land vertebrates that dominate to this day: synapsids (which includes modern mammals like us) and sauropsids (which includes crocodilian, reptiles like lizards, snakes and turtles, and dinosaurs and birds). It is defined as the period from c. 299 million years ago to the "Great Dying" mass extinction c. 252 million years ago. It is also the period when all the major land masses on Earth formed a single huge continent known that we call Pangaea, Greek for "all land", hence the choice of subtitle.

Episode 1 of the series starts in the late Carboniferous, the period before the Permian, focusing on two key adaptations that drove evolution from that time forward: the development of seeds in plants (previously, plants reproduced with spores) and the development of amniotes, vertebrate animals capable of laying eggs on land (previous vertebrates like fish and amphibians had to lay eggs in water). That sets the stage for the evolution of the two groups of amniote vertebrates I mentioned above, synapsids and sauropsids.

Here is part 1, which is available from both Eons' YouTube channel and pbs.org:

And a clip from Part 2 on PBS's YouTube channel, which deals with the pelycosaurs, synapsids who dominated the first part of the Permian. They included the famed predator Dimetrodon, often mistaken for a dinosaur due to its size and appearance but actually more closely related to modern mammals than to the dinosaurs.

And finally, the series page on PBS's website, where you can watch the 2nd and later episodes as they are released. They opened with 1 & 2 this week and the rest will be released weekly going forward.

Eons

Take a journey through the history of life on Earth.

www.pbs.org

 

[Mendalla]

I love seeing a paleontology series that focuses on something other than dinosaurs. In fact, the sauropsids were relatively insignificant in much of the Permian, with synapsids like the pelycosaurs and their successors the therapsids dominating Pangaea. It's a different world from the one we know, too. Drier overall, no major ice sheets, and only one massive continent, with the rest of the planet being an even more massive ocean. S-f writers could not have come up with a more alien world relative to Earth in the Cenozoic (the era after the extinction of the dinosaurs in which we evolved and still live). And yet, we can see the roots of what we have today in the development of the synapsids and sauropsids. The Great Dying wiped out so much of the life of the Permian, but what remained become ancestral to things like the dinosaurs as well as every vertebrate alive today. So it's an incredible time period to explore. I have been thinking for some time that I would like to do a time travel or lost world story using pelycosaurs (I have been fond of dimetrodon since childhood) and therapsids instead of the more familiar and somewhat overused dinosaurs and mammalian megafauna like mammoths and sabretooths. Might just do it now that I have some new inspiration for the idea.

 

[Mendalla]

Binged episodes 3 & 4 last night. Continues to be an good, if light on details, look at life in the Permian.

3 looks at what is known as the Guadalupian, a period in the Middle Permian named for a rock formation in Texas that was originally a massive reef. Dominant land vertebrates were therapsids known as dinocephalians and some sauropsids. Vertebrates were now getting big, though still shy of either dinosaurs or even modern megafauna like elephants and rhinos. There was a mass extinction at the end of Guadalupian but it is not counted among the "big 5" mass extinctions, though one of the hosts pretty clearly thinks it should be (make a "big 6" or even more). There was fairly significant turnover at least.

4 then looks at the late Permian, when a variety of therapsids came to dominate. Gorgonopsids were large predators and the first creatures on Earth to evolve saber teeth. Dicynodonts were small, very numerous family that included a mix of diets. Theracephalians were another family of mixed creatures. And then we had the first cynodonts, a very significant group. Why? All mammals are descendants of the cynodonts, including us. At this point, though, the cynodonts are small creatures, basically the rodents of the era. Overall, the late Permian was a real mixed bag of vertebrates, mostly on the therapsid side though sauropsids (ancestors of reptiles and birds) were certainly present.

Coming up next, of course, we have the flash finale, the end of the Permian and the largest (to date) mass extinction event.

 

[Mendalla]

One of the better known, and weirder, of the Middle Permian dinocephalians is moschops (artist's rendering based on fossils, of course):

 

[Mendalla]

And a gorgonopsid (Inostrancevia Alexandri) hunting a Scutosaurus, who were sauropsid herbivores.